Pulp treating apparatus and method

ABSTRACT

AN APPARATUS FOR TREATING PULP, COMPRISING A PAIR OF PLATENS HAVING ADJACENT PERFORATE WALLS SPACED TO FORM OPPOSING SIDES OF AN ELONGATED PROCESSING CHAMBER AND CONSTRUCTED TO CAUSE THE CHAMBER TO INCLUDE AT LEAST A PAIR OF NARROWING PRESSING ZONES INTERCONNECTED BY AN INTERMEDIATE WIDENING EXPANDING ZONE. A PAIR OF PERFORATE CONVERYING BELTS ARE LONGITUDINALLY DRIVEN THROUGH THE CHAMBER ADJACENT THE PERFORATE WALLS FOR TRNASPORTING PULP THERETHROUGH; AND CONDUITS ARE CONNECTED TO THE PRESSING AND EXPANDING ZONES FOR, RESPECTIVELY, DRAINING LIQUID THEREFROM AND SUPPLYING DILUTION LIQUID THERETO. ALSO A METHOD FOR TREATING PULP THROUGH THE EMPLOYMENT OF THIS APPARATUS.

Fehza, 1971 Bmw-UNG 33,564,631

PULP TREAT ING APPARATUS AND METHOD Filed May 18,v 1968l FG- 4 INVENTOR EL MER R. BURL /NG ATTORNEY United States Patent C 3,564,631 PULP TREATING APPARATUS AND METHOD Elmer R. Bnrling, Nashua, N.H., assignor to Improved Machinery Inc., Nashua, N.H. a corporation of Delaare Filed May 16, 1968, Ser. N0. 729,810 Int. Cl. D21c 9/02, 9/18 U.S. Cl. 8-156 7 Claims ABSTRACT OF THE DISCLOSURE An apparatus for treating pulp, comprising a pair of platens having adjacent perforate walls spaced to form opposing sides of an elongated processing chamber and constructed to cause the chamber to include at least a pair of narrowing pressing zones interconnected by an intermediate widening expanding zone. A pair of perforate conveying belts are longitudinally driven through the chamber adjacent the perforate walls for transporting pulp therethrough; and conduits are connected to the pressing and expanding zones for, respectively, draining liquid therefrom and supplying dilution liquid thereto. Also a method for treating pulp through the employment of this apparatus.

BACKGROUND OF THE INVENTION The present invention relates to pulp and paper making machinery and more specically to the provision of a new and improved apparatus and method particularly adapted for treating pulp to replace a liquid in the pulp with another liquid.

During the manufacture of cellulose pulp, there are numerous instances in which a liquid in the pulp must be replaced with another liquid. The most common of these instances, of course, arises when liquor and contained spent chemicals must be removed from the pulp and replaced by cleaner dilution water. Conve-ntionally, this replacement operation is generally performed by agitating the pulp in a slurry diluted to extremely low pulp consistency and then screening the pulp on a wire screen while it is being washed by additional dilution water. This conventional replacement operation, however, requires the employment of vast quantities of dilution liquid and is, for this reason, ineflicient and disadvantageous.

SUMMARY OF THE INVENTION The principal object of the present invention is to provide a new and improved apparatus which is particularly constructed and arranged to efficiently perform such a replacement operation without the necessity for the aforementioned vast quantities of dilution liquid.

Another object of the invention is to provide a new lanti improved method for performing such a replacement operation through the employment of this apparatus.

These objects, and those other objects and advantages of the invention which will become apparent from the following description taken in connection with the accompanying drawings, are attained by the provision of a new and improved pulp treating apparatus which generally considered may comprise a plurality of opposed platens cooperating to provide an elongated processing chamber which includes a pluarilty of narrowing pressing zones interconnected by an intermediate widening expanding zone. A conveying means is provided in the processing chamber for directing pulp longitudinally therethrough such that pulp is conveyed successively through a first of the pressing Zones, the expanding zone, and the other of pressing zones. In addition, a means communicates with each of the pressing zones for draining liquid therefrom; and a ice means communicates with the expanding Zone for injecting dilution liquid thereto.

IBRIEF DESCRIPTION OF THE DRAWINGS Referring to the drawings:

FIG. l is a schematic View illustrating a pulp treating apparatus constructed in accordance with one embodiment of the invention;

FIG. 2 is an elevational sectional view of the pulp treating apparatus illustrated in FIG. l;

FIG. 3 is an elevational sectional view taken on line 3 3 in FIG. 2, looking in the direction of the arrows;

FIG. 4 is an elevational sectional view taken on line 4-4 i-n FIG. 2, looking in the direction of the arrows; and

FIG. 5 is an elevational sectional view generally similar to FIG. 2, but illustrating a pulp treating apparatus constructed in accordance with a modied embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring more particularly to the drawings wherein similar reference characters designate corresponding parts D throughout the several views, FIGS. 1 through 5 illustrate apparatuses constructed in accordance with two embodiments of the invention which, although particularly adapted for pulp washing use, may be alternatively employed in many other situations in which a liquid in the pulp is to be replaced with another liquid. More specically, FIGS. l through 4 illustrate a pulp treating apparatus, designated generally as 10, comprising a pair of elongated press platens 12, 14 which are disposed in opposing relationship. The platens 12, 14 include adjacent spaced walls 16, 18, respectively, which cooperate to form opposing sides of an elongated processing chamber 20 between the platens 12, 14. The opposing lateral sides of this processing chamber 20 are, as illustrated in FIGS. 3 and 4, closed by abutting extensions 22, 24 of the platens 12, 14.

The walls 16, 18 are perforated by apertures 26 throughout their lengths and are particularly constructed to cause the processinf chamber 20 to include a plurality of narrowing cross-section pressing zones interconnected by at least one intermediate widening cross-section expanding Zone. More particularly, adjacent the inlet end 20a of the processing chamber 20, the walls 16, 18 include opposing wall sections 28, 30 which converge as they extend longitudinally from such inlet end 20a. This convergence of the wall sections 28, 30, as will be seen, forms the portion of the processing chamber 20 therebetween into a first vertically tapering pressing zone 32. Similarly, adjacent the discharge or outlet end 20b of the processing chamber 20, the walls 16, 18 include opposing wall sections 34, 36 which converge as they extend longitudinally towards the discharge end 20b. This convergence of the wall sections 34, 36, again as will be seen, forms the portion of the processing chamber 20 therebetween into a second vertically tapering pressing zone 38.

Intermediate the pressing zones 32, 38, and immediately downstream from the pressing zone 32, the walls 16, 18 include opposing wall sections 40, 42 which diverge as they extend longitudinally from the pressing chamber 32 and thence extend substantially parallel for a short distance before their junctures with the wall sections 34, 36. This construction of the wall sections 40, 42 forms the portion of the processing chamber 20 therebetween into a vertically widening expanding zone 44 which, after attaining its maximum width, retains such width for a short distance prior to the commencement of the second pressing zone 38. It will be seen that, due to this construction of the Walls 16, 18, pulp conveyed longitudinally through the processing chamber 20 from the inlet end 20a to the discharge end 2Gb is directed successively through the first pressing zone 32, an expanding zone 44, and the second pressing zone 38 before its discharge from the processing chamber 20.

The platens 12, 14 each contain passage means 46 which communicate with the rst pressing zone 32 through cavities 47 and the apertures 26 in the wall sections 28, 30. The platens 12, 14 also each contain passage means 48 which communicates with the second pressing zone 38 through cavities 49 and the apertures 26 in the wall sections 34, 36. The passage means 46, 48, as illustrated in FIG. l, each are connected by suitable conduits or pipes 50, S2 to a conventional vacuum pump 54 which serves to create suflicient vacuum in the conduits 50, 52 and cavities 47, 49 to draw liquid expressed from pulp by the pressing zones 32, 38 from the processing chamber 20. Alternatively, however, the passage means 46, 48 could be otherwise suitably connected to discharge the liquid expressed from the pulp in the pressing zones 32, 38.

The platens 12, 14, in addition, contain passage means 56, 58, respectively, which communicate with the expanding zone 44 through cavities 59 and the apertures 26 in the wall sections 40, 42. These passage means 56, 58, as illustrated in FIG. 1, are connected by suitable conduit means 60 to a source 62 of pressurized dilution liquid such that, during the operation of the apparatus 10, pressurized dilution liquid is continuously supplied to the expanding zone 44 through the passage means 56, 58. The dilution liquid thus supplied to the expanding zone 44 will, of course, be washing water in those instances in which the apparatus is employed as a pulp washer but in other applications of the apparatus 10 may be other suitable liquids such as, for example, water containing bleaching chemicals or organic liquids. Furthermore, although both of the passage means 56, 58 are illustrated as supplying dilution liquid to the expanding zone 44, it will be understood that alternatively only one of such passage means 56, 58 could be so employed in which event the other thereof could be used for draining excess liquid from the expanding zone 44.

A conveying apparatus is provided for conveying pulp longitudinally through the processing chamber and hence successively through the rst pressing zone 32, the expanding zone 44, and the second pressing zone 38. As illustrated in FIGS. 1 through 4, this conveying apparatus comprises a rst or lower endless conveying belt or web 64, perforated throughout its length by apertures 66, which is disposed longitudinally through the processing chamber 20 and entrained around the platen 14. In addition, this conveying apparatus also includes, in the embodiment of the invention illustrated in FIGS. l through 4, a second or upper endless conveying belt or web 68, perforated throughout its length by apertures 70, which is disposed longitudinally through the processing chamber 20 and entrained around the platen 12. The conveying belts 64, 68 are supported at their end turns by end rollers 72 and intermediate their end turns are supported and guided by idler rollers 74 carried by their respective surrounded ones of the platens 12, 14. The conveying belts `64, 68 are suitably tensioned such that during the operation of the apparatus 10, as shown in FIG. 2, they engage the one of the walls 16, 18 of the platen they surround and assume the relative converging, diverging, and reconverging configuration of the walls 16, 18 which was aforedescribed. The conveying belts 64, 68 are longitudinally driven to transport pulp supplied to the processing chamber 20 at the inlet end 20a through the processing chamber 20 and out the discharge end 20b thereof by a conventional driving means such as the electric motor 76. The motor 76, as illustrated in FIG. l, is connected by suitable gearing, designated generally as 79, to the end rollers 72 to rotate the latter at a controlled speed whereby the end rollers 72 serve as driving rollers for the conveying belts 64, 68.

In the operation of the pulp treating apparatus 10, pulp having a ber content preferably within the range of 1 to 5% is continuously supplied to the inlet end 20a of the processing chamber 20 by a suitable feed apparatus; and treated pulp discharged at the discharge end 20b of the processing chamber 20 is removed by a suitable discharge apparatus. As illustrated in FIGS. 1 and 2, the feed apparatus for the apparatus 10 comprises a feed conduit 78, suitably connected to receive pulp from a source (not shown), which projects intermediate the conveying belts 64, 68. The discharge apparatus comprises a conventional endless conveying belt or web 80, driven by the motor 76 through a driving roller 82, disposed in horizontal alignment with the endless conveying belt 64. It will be understood, however, that other feed and discharge apparatus could be alternatively employed for these purposes.

During the operation of the aforedescribed pulp treating apparatus 10, the pulp supplied by the feed conduit 78 to the inlet end 20a of the processing chamber 20 forms a pulp mat which horizontally extends the Width of the processing chamber 20 and vertically the distance between the conveying belts 64, 68 at the location P it is fed thereto. The conveying belts 64, 68 convey this pulp mat through the first pressing zone 32 where, due to the converging construction of the wall sections 28, 30, the mat is pressed between the platens 12, 14 to exo tract liquid from the mat. The conveying ybelts 64, 68

then convey the pressed mat to the expanding zone 44 where, due to the enlarged cross-section of the zone 44, the mat quickly expands and attains a relatively porous condition which enables it to rapidly absorb dilution liquid supplied by the passage means 56, 58. The mat and its contained dilution liquid are thence transported by the conveying belts 64, 68 to the second pressing Zone 38 where the mat is repressed to extract a portion of its carried dilution liquid and thereafter discharged onto the conveying belt 80 which transports it to the succeeding stage of the paper making operation.

FIG. 5, wherein parts similar to those previously described with reference to the pulp treating apparatus 10 are designated by the reference character for their similar previously described part followed by the suffix c, illustrates a pulp treating apparatus 10c constructed in accordance with a modied embodiment of the invention. The pulp treating apparatus 10c differs from the aforedescribed pulp treating apparatus 10 only in that the pressing zones 32e, 38e, rather than being interconnected by only a single intermediate expanding zone, are interconnected by a pair of intermediate expanding zones 44C which are spaced by a pressing zone 84. The pressing zone 84 is identical in construction to the aforedescribed pressing zones 32, 38 and, hence, is vertically bounded by converging wall sections 86, 88 of the walls 16C, 18C. The platens 12C, 14c include passage means 90, 92 cornmunicating through cavities 93 with the pressing zone 84 and connected in the manner shown in FIG. 1 to a suitable vacuum pump (not shown). The passage means 56C, 58C moreover, in this embodiment of the invention, may either be connected such that the same dilution liquid is supplied to the pulp mat in both expanding zones 44c or, alternatively, such that different dilution liquids are supplied inthe expanding zones 44C.

The operation of this embodiment of the invention is believed to be apparent from the aforegoing description taken in connection with the accompanying drawings.

From the aforegoing it Will be seen that I have provided a new and improved apparatus which, due to relatively high consistency of the pulp it treats and the manner in which the pulp is pressed and then released to absorb liquid, operates in a highly eiiicient manner. It will moreover be seen that this apparatus performs its pressing and releasing actions on the mat without either disrupting the mat or dislodging the component bers from their relative positions.

From the aforegoing it will also be seen that I have provided a new and improved pulp treating method basically comprising the steps of introducing the pulp into an elongated processing chamber having a plurality of narrowing pressing zones interconnected by an intermediate widening expanding zone, conveying the pulp longitudinally through this processing chamber to cause the pulp to pass alternately through the pressing and expanding zones, and introducing diluent liquid into the pulp during its passage through the expanding zone.

From the aforegoing it will be seen that I have provided new and improved means for accomplishing all of the objects and advantages of my invention. It will be understood, however, that, although I have illustrated and hereinbefore specifically described only two embodiments of my invention, the invention is not limited merely to these two embodiments but rather contemplates other embodiments and variations Within the scope of the following claims.

Having thus described my invention, I claim:

1. An apparatus for treating pulp, comprising a plurality of platens having adjacent walls opposed in spaced relationship to bound opposite sides of a processing chamber therebetween; said processing chamber having an inlet end and a discharge end; said walls successively relatively converging, diverging and reconverging as they extend from the chamber inlet end towards the chamber discharge end whereby said processing chamber has portion defining successively a first transversely narrowing pressing zone, a transversely widening expanding zone and a second transversely narrowing pressing zone as it extends from its inlet end towards its discharge end; an endless porous conveying web extending longitudinally through said processing chamber adjacent each of said walls for directing pulp through said processing chamber whereby the pulp is conveyed successively through said rst pressing zone, said expanding zone and said second pressing zone; said conveying webs being tensioned to have the relatively converging, diverging and reconverging relationship of said walls; iirst drainage conduit means connected to said processing chamber at said rst pressing zone for discharging liquid pressed from pulp in said first pressing zone from said processing chamber; second drainage conduit means connected to said processing chamber at said second pressing zone for discharging liquid pressed from pulp in said second pressing zone from said processing chamber; and supply conduit means connected to said processing chamber for supplying dilution liquid to said processing chamber at said expanding zone said porous conveying webs permitting said discharge of liquid pressed from the pulp.

2. A pulp treating apparatus according to claim 1, further comprising the conduit means connected to said processing chamber at said expanding Zone being connected to said expanding zone through at least one of said walls of said platens.

3. A pulp treating apparatus according to claim 1, further comprising the conduit means connected to said processing chamber at least at one of said pressing zones being connected to the pressing zone through at least one of said walls of said platens.

4. A pulp treating apparatus according to claim 1, further comprising said platen walls being perforate, and the conduit means connected to said processing chamber at said pressing and expanding zones being connected to CII said pressing and expanding Zones, respectively, through said walls and said porous conveying webs.

5. A pulp treating apparatus according to claim 1, further comprising said platen walls relatively rediverging and again reconverging whereby said processing chamber includes a plurality of expanding zones, each intermediate and interconnecting a pair of pressing zones, and has a pressing Zone at each of its inlet and discharge ends, and wherein conduit means is connected to said processing chamber at each of said pressing and expanding zones for draining liquid therefrom and supplying liquid thereto, respectively.

6. A pulp treating apparatus according to claim 1, further comprising said platen walls having perforate portions bounding said expanding zone, said supply conduit means being connected to said expanding Zone through one of said walls and the thereadjacent porous conveying web, and means connected to said expanding zone through the other of said platen walls and the thereadjacent conveying web for draining liquid from said expanding zone.

7. A method of treating pulp containing liquid, comprising the steps of introducing the pulp to one end of a processing chamber bounded along opposite sides by platen walls which successively relatively converge, diverge and reconverge as they extend from said one end of the processing chamber towards the other end thereof; directing the introduced pulp through said processing chamber towards its said other end by endless porous conveying webs which extend adjacent each of said platen walls and which are tensioned to have the aforesaid relative converging, diverging and reconverging relationship of said platen walls, discharging the liquid pressed from the pulp g by the relatively converging portions of said platen walls from the processing chamber through perforations in said platen walls separately from the liquid pressed from the pulp by the relatively reconverging portions of said platen walls whereby the first mentioned liquid is removed from the processing chamber prior to the pulp being directed along the relatively diverging portions of the platen walls; supplying dilution liquid to the pulp while the pulp is directed along the relatively diverging portions of the platen walls; and discharging the pulp from said other end of said processing chamber.

References Cited UNITED STATES PATENTS 3,241,343 3/1966 Yazawa 68-181X 3,454,970 7/ 1969 Sutherland 162-60X 2,552,078 5/1951 Williams 68-44 3,453,951 7/1969 Malarkey, Jr. 210-401X FOREIGN PATENTS 1,338,627 8/1963 France 68-44 HOWARD R. CMINE, Primary Examiner A. D. ANDREA, J R., Assistant Examiner U.S. Cl. X.R. 68-44, 204; 162-56, 60; 210-400 

